During the coming year we plan to follow intensively six infants from 17 to 29 months of age, gathering data on language, symbolic play, memory, and inference every three weeks in order to clarify the bases for the growth spurt in language and memory that seems to occur during this intervel. Additionally, we plan to initate a study of children between one and three years of age to confirm a relation found last year between stable heart rate ranges and high heart rate, on the one hand, and a vulnerability to display of inhibition and behavioral signs of anxiety in uncertain contexts, on the other.